1. Field of the Invention
The present invention relates to a tank, which is made of resin, for a heat exchanger, and particularly to a structure of the tank into which fixing parts are inserted. For example, the present invention is preferably applied to an automotive radiator.
2. Description of Related Art
Conventionally, the kind of tank for a heat exchanger disclosed in Japanese Patent Application Laid-Open No. Hei 1-131896 has been proposed. In this conventional mechanism shown in FIGS. 5 and 6, a resin tank 110 for an automotive radiator has a gutter-shaped cross section. A receiving portion 120 is formed integrally with an outer wall surface of the tank 110 and the tank receives a nut 130 at the receiving portion 120. The nut 130 fixes a shroud of a radiator cooling blower fan (not shown) on the tank 110.
A mechanism for receiving the nut 130 is described in detail. In FIGS. 5 and 6, the receiving portion 120 has a base wall (basic wall) 121, a front wall 122 and side walls 123 and 124 and is formed into a box shape having an opening at an upper portion thereof. A round hole 125 is provided at the front wall 122 so that a male screw axial portion of a bolt may be inserted into the nut 130.
At a top surface-of the base wall 121, two elastic leg pieces 126 and 127 extending upward are formed integrally. A protrusion portion 131 is formed at a front top portion of the nut 130. An engagement groove 128 engaged with the protrusion 131 is formed on an upper portion of the round hole 125.
The nut 130 is inserted into the receiving portion 120 from an upper side of the receiving portion 120 in such a manner that the nut 130 moves downward while deforming the elastic leg pieces 126 and 127 elastically toward a rear side of the tank 110. After the protrusion 131 enters into the engagement groove 128 and has been engaged therewith, the nut 130 is fixedly received inside the receiving portion 120 by an engagement between the protrusion 131 and the engagement groove 128 and elastic pressure force by the elastic leg pieces 126 and 127.
In the conventional mechanism, the receiving portion 120 has the round hole 125 at the front wall 122 of the receiving portion 120. Since an opening direction of the circular hole 125 is orthogonal to an opening and closing direction of a forming die for forming the tank 110, in order to provide the circular hole 125, an additional mechanism of an undercut treatment such as a sliding core or the like should be provided at the forming die.
FIG. 7 illustrates the cross-sectional view of the forming die which corresponds to the cross section in FIG. 6. A special sliding core 163 is necessary to form the round hole 125 in addition to a lower die 161 and a upper die 162. An arrow Y in FIG. 7 illustrates the opening and closing direction of the lower die 161 and the upper die 162 and an arrow Z illustrates a moving direction of the sliding core 163.
Therefore, in the conventional mechanism, it is necessary to provide the undercut treatment such as the sliding core 163 or the like in the forming die, the cost for forming the tank 110 thereby being increased.